by Renata Trister DO
Aromatherapy is actually a form of herbal medicine. However, instead of using the entire herb, it employs the fragrant “essential oil” that is released when a fresh herb is compressed or subjected to chemical extraction. Essential oils are also often used as fragrances in cosmetics and bath products.
When employed medicinally, essential oils are often evaporated into the air through the use of a humidifier. The famous Vicks VapoRub is a gel form of the essential oils of peppermint, eucalyptus, and camphor. Certain essential oils may also be applied directly to the skin or clothes so they will release their odor near the patient. Some essential oils are designed to be taken by mouth, but this is an uncommon usage.
What Is Aromatherapy Used For?
Inhaled aromatherapy has become a popular, gentle treatment to reduce mild anxiety. It has also been tried for a variety of other conditions, including respiratory problems, postsurgical nausea, menstrual pain, and tension headaches.
Topical treatment with essential oils has shown possible value for fungal infections and hair loss. Essential oils specifically designed for oral use have shown some promise for various digestive and respiratory problems.
What Is the Scientific Evidence for Aromatherapy?
There is a major difficulty in studying aromatherapy by inhalation: how to conduct a double-blind, placebo-controlled trial. For the results of a study to be truly reliable, both participants and researchers must be kept in the dark regarding participants who received real treatment and who received placebo. Although it may be possible to keep researchers in the dark regarding which group is which, participants will certainly be aware of whether they smell something or not! This is a problem because it has been shown that when researchers create expectations about the effects of certain aromas, those effects may occur simply because of those expectations. Researchers have used various clever compromises in an effort to partially solve this problem. For example, some studies used a control group that received an aromatic substance believed to be ineffective, without informing the members of the control group that this alternate aromatic substance will not work. Unfortunately, it is just as hard to prove that an aromatic substance is ineffective as it is to prove that it is effective! If the placebo in a study is just as effective as the tested treatment, the study will falsely indicate that the tested treatment is ineffective. Furthermore, many odors already have associations attached them, based on cultural patterns. Lavender oil, for example, conjures up for many people memories of their grandmother. It simply is not possible to remove such expectations.
In other studies, researchers tricked participants in the control group and told them that they might be receiving an active but odorless treatment, when in fact they were simply given an inactive treatment without much in it. Still other studies managed to find ethical ways of keeping their study participants in the dark regarding whether they were enrolled in a study at all, and then introduced the odors surreptitiously. Partially effective compromises such as these are necessary.
Thus, everything written below about true aromatherapy—that is, inhalation of an aroma—must be taken with a grain of salt.
These problems do not arise to the same extent in studies of essential oils taken by mouth or applied directly to the skin.
Inhalation of Essential Oils
Alzheimer’s Disease and Other Forms of Dementia
Preliminary controlled trials suggest that various forms of aromatherapy might be helpful for calming people with Alzheimer’s disease and other forms of dementia. For example, in one interestingly designed, but very small, study, a hospital ward was suffused with either lavender oil or water for two hours. An investigator who was unaware of the study’s design and who wore a device to block inhalation of odors entered the ward and evaluated the behavior of the 15 residents, all of whom had dementia. The results indicated that use of lavender oil aromatherapy modestly decreased agitated behavior. A less rigorous study also reported benefit with lavender. However, people with dementia tend to lose their sense of smell, making this approach seem somewhat limited in its usefulness. Essential oil of lemon balm has also shown promise for this purpose; in a double-blind study of 71 people with severe dementia, use of a lotion containing essential oil of lemon balm reduced agitation compared to placebo lotion. Here, absorption through the skin may have played a role.
Several relatively poorly designed studies hint that aromatherapy combined with massage may help to relieve anxiety in people without Alzheimer’s disease. Another study suggests that aromatherapy with geranium oil might modestly reduce anxiety levels (again in people without Alzheimer’s).
Researchers have also studied aromatherapy as a potential treatment for the cognitive (eg, memory) impairments caused by dementia. In a small study, 28 elderly people with dementia (including 17 people with Alzheimer’s disease) were exposed to rosemary and lemon oil in the morning and lavender and orange in the evening for 28 days. When researchers compared the dementia assessment scores during the treatment period to the scores from the previous month (control period without aromatherapy), they found that all of patients experienced an improvement in their symptoms.
A controlled study suggests that inhalation of black pepper vapor may reduce the craving for cigarettes. 8 In this trial, a total of 48 smokers used cigarette substitute devices that delivered black pepper vapor, menthol, or no fragrance. The results showed that use of the black pepper-based dummy cigarette reduced symptoms of craving for the first morning cigarette.
A topical ointment known as Tiger Balm has also shown promise for headaches. Tiger Balm contains camphor, menthol, cajaput, and clove oil. A double-blind study enrolling 57 people with acute tension headache compared the application of Tiger Balm to the forehead against placebo ointment as well as the drug acetaminophen (Tylenol). The placebo ointment contained mint essence to make it smell similar to Tiger Balm. Real Tiger Balm proved more effective than placebo and just as effective and more rapid-acting than acetaminophen.
In a trial of 66 women waiting to undergo abortions, 10 minutes of inhaling the essential oils of vetivert, bergamot, and geranium failed to reduce anxiety significantly more than placebo treatment. In another study, rosemary oil failed to reduce tension during an anxiety-provoking task and might have actually increased anxiety.
However, other studies have shown more favorable effects. In one such trial, researchers assessed the anxiety level in 340 dental patients while they were waiting for their appointment. Those that inhaled the scent of lavender showed lower levels of anxiety compared to the control group. In another study, 150 patients were randomized to one of three treatment groups: control (standard care), standard care plus lavender, or sham (standard care plus another kind of oil). Those that were in the lavender group did experience a reduction in their level of anxiety.
Taking a different approach, researchers evaluated the effects of massage therapy done with essential oils on people suffering from anxiety and/or depression while undergoing treatment for cancer. The treatment did appear to provide some short-term benefits.
Weak evidence suggests that inhaled peppermint oil might relieve postsurgical nausea. Peppermint was associated with improved nausea symptoms in a small randomized trial of 35 women after nonemergency cesarean section compared to placebo aromatherapy and standard antiemetic drugs.
Inhaled peppermint oil may also be helpful for relieving mucus congestion of the lungs and sinuses; however, there is only weak supporting evidence for this use.
In one study, abdominal massage with lavender, rose, and clary sage reduced menstrual pain to a greater extent than an almond oil placebo. In another study, acupressure combined with lavender, rosemary, and peppermint aromatherapy was more effective than acupressure alone for treating the shoulder pain caused by a certain form of stroke.
Controlled studies have evaluated proprietary-inhaled aromatherapy preparations for treating the common cold and preventing flare-ups of chronic bronchitis, but the results were marginal at best. A study involving vapor rub found a more positive effect, though. One hundred and thirty-eight children (aged 2-11 years old) with upper respiratory infection were randomized to receive vapor rub (camphor, menthol, and eucalyptus oils), petroleum jelly, or no treatment. The children who had vapor rub applied before bedtime experienced an improvement in their nighttime symptoms (eg, less coughing, less nasal congestion) compared to the other two groups.
More studies are on the way as the methods to research aromatherapy become more perfected.